Problem: Solve the system of equations. $\begin{aligned} & 5x-4y = -10 \\\\ & y=2x-5 \end{aligned}$ $ x=$
Answer: We are given that $ y = {2x-5}$. Let's substitute this expression into the first equation and solve for $x$ as follows: $\begin{aligned} 5x-4{y}&=-10\\\\ 5x-4\cdot({2x-5})&=-10\\\\ 5x-8x+20& = -10\\\\ -3x&=-30\\\\ x&=10 \end{aligned}$ Since we now know that $ x={10}$, we can substitute this value into the second equation to solve for $y$ as follows: $\begin{aligned} y &= 2\cdot {x}-5 \\\\ y&=2\cdot{10}-5\\\\ y&=15 \end{aligned}$ This is the solution of the system: $\begin{aligned} &x = 10 \\\\ &y=15 \end{aligned}$